Conventionally, transparent plastics are widely used as transparent substrates for a display for electronic equipment such as personal computers, TVs, and cellular phones. In spite of the advantages of being lightweight, being hard to be damaged, and the like as compared with glass which is also a transparent substrate, the transparent plastics possess a low hardness, are easily scratched, and easily have electrostatic dust attached thereto. For this reason, the plastic substrate is generally provided with a hard coat layer, an antistatic layer, and the like on the surface.
In addition, a reflection preventing layer may also be provided on the display of electronic equipment in order to suppress external image reflection, light reflection, glare, and the like and to increase visibility of a screen.
More recently, according to the demand for decreasing the weight and size (thickness) of electronic equipment, a reflection preventing film possessing both antistatic characteristics and reflection preventing capability has been proposed.
As an example of such a reflection preventing film, JP-A-9-288202 describes a reflection preventing film made from a high refractive index layer containing metal alkoxide, colloidal metal oxide, and/or a metal halide as major components, a low refractive index layer of an amorphous fluororesin with a refractive index of 1.36 or less formed on the high refractive index layer, and a coating layer containing organic polysiloxane, which contains a fluorine-based surfactant, as a major component formed on the low refractive index layer. JP-A-11-211901 discloses a reflection preventing film made from a low refractive index layer of a fluorine-containing compound with a refractive index of about 1.4 formed on a hard coat layer in which fine particles of metal oxide such as zinc antimonate fine particles are dispersed. JP-A-11-218604 (U.S. Pat. Nos. 6,310,858, 6,383,559) discloses a reflection preventing film made from a low refractive index layer with a refractive index from 1.20 to 1.55 formed on an antistatic layer of a polymer binder having an anionic group in which fine particles of metal oxide such as antimony-doped tin oxide (ATO) and tin-doped indium oxide (ITO) are dispersed.
The reflection preventing films disclosed in these prior art documents, however, do not necessarily satisfy the demanded transparency, mechanical strength, antistaticity, and reflection preventing characteristics. In particular, the addition of metal oxide fine particles unduly impairs transparency of the substrate film, although the antistatic characteristics can be provided.
JP-A-11-72602 discloses a substrate with a reflection preventing layer made from a low refractive index layer of a fluorine-containing polymer with a refractive index of 1.36 or less formed on a thin metal oxide film of antimony pentaoxide fine particles. However, this metal oxide thin film cannot exhibit sufficient strength and hardness. Moreover, the resulting substrate with a reflection preventing layer does not satisfy sufficient reflection preventing performance.